USB to Digital Coax 24Bit?
Mar 21, 2009 at 10:50 PM Thread Starter Post #1 of 40

sirmasterboy

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Hi all,

I'm looking for a device for my laptop that will convert from USB to digital coaxial so I can hook my laptop up to a home theater receiver to send over DD and DTS signals. I believe it needs to support 24bit for the DD and DTS signals.

Thanks
 
Mar 22, 2009 at 10:33 AM Post #3 of 40

obobskivich

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these will all do things via stereo, as none of them are multi-channel sources, nor are they DTS/AC-3 capable (I know the E-MU can passthrough, but that requires having a DTS or AC-3 source to connect to it (at which point, why bother?) or having said source on the PC, and I'm not 100% on the specifics there)

does your reciever have discrete analog pre-ins?
 
Mar 22, 2009 at 6:46 PM Post #4 of 40

sirmasterboy

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Thanks for the suggestions so far guys.

Let me try to be a bit more detailed in what I need though. I don't think most of you quite understand.

I'm turning my Laptop into a media center for playing movies. All of my movies have AC3 or DTS tracks on them. My laptop does not have a digital output so I have no way of connecting it to my receiver to play the multichannel tracks.

All of those things are far too expensive for the simple task I need done. Currently I am looking at this product which would work but I want Coax instead of Optical.
Newegg.com - Creative Sound Blaster X-Fi Surround 5.1 SB1090 5.1 Channels 24-bit 96KHz USB Interface Sound Card - Sound Cards

All I need is something simple and cheap that can do SPDIF pass-through so my receiver can do all the decoding, no A/D or D/A.

Yes my receiver does have discrete analog inputs but why would I want to convert the signal to analog prior to it hitting the receiver when it is perfectly capable of decoding AC3 and DTS itself. I would need an expensive A/D converter to achieve this when all I need is a cheap USB to Coax to pass the raw SPDIF bit stream to my receiver, digital all the way.

Thanks
 
Mar 22, 2009 at 7:44 PM Post #5 of 40

sirmasterboy

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After looking long and hard, I don't think I can beat the Creative for the price.

Specs say it will do what I want.

Creative USB Sound Blaster X-Fi Surround 5.1 Sound Card - Get more out of your music and movies

Playback: USB 2.0: Stereo/ Surround ≤ 24-Bit/96kHz 5.1

USB 1.1: Stereo ≤ 24-Bit/96kHz 5.1
Surround 16-Bit/48kHz

• Optical out (TOSLINK) 1

1 Optical Out supports stereo SPDIF out and pass through of multi-channel DVD sound.

Ill just have to get an Optical Splitter like this:
Amazon.com: Nyrius SW100 Digital Audio Optical Toslink 3-Way Selector Switch for Fiber Optic Home Theater Connections (Silver): Electronics
 
Mar 22, 2009 at 9:59 PM Post #6 of 40

sirmasterboy

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After some more playing around I found my solution and I'm closing this thread.

It turns out I can hook my Laptop to my TV via HDMI and hook my TV to my Receiver via Toslink and enable SPDIF pass-through on my Laptop and the bit stream AC3 or DTS passes right through my TV to my Receiver untouched. Now all I need is a cheap Toslink switcher, since I have 2 Toslink sources and 1 input on my Receiver.
 
Mar 23, 2009 at 12:05 AM Post #7 of 40

obobskivich

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honestly, this isn't a "simple task", just because it can piece together in your head doesn't mean the equipment is "simple"

glad the HDMI port works

as far as an "optical switcher", amazon, monoprice, etc

and the reason for the analog (why do you need an A/D? you aren't digitizing crap in this chain) output is that most multi-ch sources are designed with analog out in mind (for example soundcards), this is slowly changing as people start hooking receivers up with digital inputs
 
Mar 23, 2009 at 1:29 AM Post #8 of 40

sirmasterboy

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I guess I realize that it isn't a simple task to convert USB to SPDIF. The difficult part is reducing jitter and dealing with the full 24bits on USB.

What I guess I meant by simple was no A/D or D/A converting. I figured it would be simpler and cheaper if it didn't have to convert between analog and digital.

Any real thing I should be aware of when shopping for an optical switcher? What about an Optical to Coax converter?

I have seen both for about $20 on amazon and the reviews seem like they work for what I need.

For a switcher I would be concerned about the switch wearing out and possible signal loss. On the converter I would be worried about signal loss. Should I really worry about these things?
 
Mar 23, 2009 at 1:36 AM Post #9 of 40

obobskivich

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Quote:

Originally Posted by sirmasterboy /img/forum/go_quote.gif
I guess I realize that it isn't a simple task to convert USB to SPDIF. The difficult part is reducing jitter and dealing with the full 24bits on USB.

What I guess I meant by simple was no A/D or D/A converting. I figured it would be simpler and cheaper if it didn't have to convert between analog and digital.

Any real thing I should be aware of when shopping for an optical switcher? What about an Optical to Coax converter?

I have seen both for about $20 on amazon and the reviews seem like they work for what I need.

For a switcher I would be concerned about the switch wearing out and possible signal loss. On the converter I would be worried about signal loss. Should I really worry about these things?



its either going to work, or not work
wink.gif


as far as the logic in your post, I see it, and agree 100%, but in reality, at least today, most users with soundcards still use analog outs, so its just worked into the parts cost and design *shrug*
 
Mar 23, 2009 at 7:45 PM Post #10 of 40

gregorio

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Quote:

Originally Posted by sirmasterboy /img/forum/go_quote.gif
I guess I realize that it isn't a simple task to convert USB to SPDIF. The difficult part is reducing jitter and dealing with the full 24bits on USB.


Jitter is a bit of a non issue. Most DACs can now easily deal with jitter.

If all you are dealing with is DD and DTS you do not need to deal with 24bit as neither of these is a 24bit format. DD uses data compression and the actual bit rate is 448kbps (for all six channels)! DTS is about 768kbps (if memory serves). DD and DTS end up being well below 16bit data rates, let alone 24bit, although the bit depth (like in MP3s) varies according to program detail.

G
 
Mar 23, 2009 at 11:39 PM Post #11 of 40

obobskivich

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Quote:

Originally Posted by gregorio /img/forum/go_quote.gif
Jitter is a bit of a non issue. Most DACs can now easily deal with jitter.

If all you are dealing with is DD and DTS you do not need to deal with 24bit as neither of these is a 24bit format. DD uses data compression and the actual bit rate is 448kbps (for all six channels)! DTS is about 768kbps (if memory serves). DD and DTS end up being well below 16bit data rates, let alone 24bit, although the bit depth (like in MP3s) varies according to program detail.

G



but DTS/DD can be released as a 24-bit format, so wouldn't you not want Windows' USB Streaming Audio drivers handling the dithering process?

just because the bits aren't "used", shouldn't you still be passing the blank spaces along, instead of assuming the system will cleanly/correctly lop them off?
 
Mar 24, 2009 at 12:39 AM Post #12 of 40

sirmasterboy

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Is this not 24bit?

DTS 96/24

DTS 96/24 allows the delivery of 5.1 channels of 24-bit, 96 kHz audio and high quality video on the DVD-Video format. Prior to the invention of DTS 96/24, it was only possible to deliver two channels of 24-bit, 96 kHz audio on DVD-Video. DTS 96/24 can also be placed in the video zone on DVD-Audio discs, making these discs playable on all DTS compatible DVD players.

Most of my movies have these tracks on them. They are 1536 Kb/s
 

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